<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
</head>
<body>
	<script type="text/javascript">
		//求半径为r的圆的面积和周长(r是参数)
		//π Math.PI表示π值
		function area(r){
			let s = Math.PI * r * r
			let l = 2 * Math.PI * r
			// \ 转义字符 \n 换行 \t 空格\
			return "面积是" + s + "\n周长是" + l
		}
		console.log(area(4))
		</script>
</body>
</html>